A crustal-scale cross-section of the south-western Alps combining geophysical and geological imagery

A geotransect across the south-western Alps from the Pelvoux Massif (external French Alps) to the Dora-Maira massif (internal Italian Alps), through the Monviso ophiolitic complex, was investigated in the framework of the 'Geo-France 3D Alpes' programme. A new interpretative crustal-scale section across the south-western Alps is proposed, combining geological and geophysical 2D/3D data. The Apulian mantle (i.e. the Ivrea body) might be divided into two rigid pieces separated by the downward prolongation of the Penninic frontal thrust. These mantle indenters drive the decoupling of the European crust. Beneath the high to ultra-high pressure metamorphic nappes, the deep structure results from the stacking of crustal slices extracted from the European lithosphere. The proposed structural model provides a basis for discussing the evidence of the crustal-scale partitioning of the current strain pattern as well as the location of the seismicity.